Internet of Things

The new single and dual band Wi-Fi modules by Qualcomm

Internet of Things (IoT) is used to describe a phenomenon where home PCs as devices are gradually being replaced by "intelligent objects". Instead of being at the centre of human attention, as it is currently the case with the Internet, IoT will inconspicuously be assisting humans in their daily tasks. The objective of these ever-shrinking tiny computers is to help people in their everyday lives without distracting them or even being noticed (See: Wikipedia). According to official estimates, more than 25 billion such devices will be connected to each other over the Internet by 2020. With respect to Wi-Fi, the industry is looking for solutions that are even smaller and more compact, while costing less and less. Low power consumption is also an issue in IoT, since such devices are often powered by batteries. CODICO offers two Wi-Fi modules tailored specifically to meet these requirements, which were developed by market leader Qualcomm.

We already presented the single-band DNSA-141 Wi-Fi module in detail in our 2014 Impulse issue. Now we added a second module that also supports dual-band (2.4 GHz and 5 GHz) and diversity at 2.4GHz, the DNSA-144. Although both modules are produced and marketed by Wistron, they are based on the SP141 and SP144 Wi-Fi reference designs by Qualcomm. Therefore, Wistron appears as an original design manufacturer (ODM), which precisely observes the reference design specifications and manufactures according to these. While Wistron delivers the hardware, Qualcomm exclusively provides technical support and development boards. A support page was set up specifically for this purpose, where users can download the entire support package (demos, drivers, datasheets, user guides, etc.):

Both module solutions are based on the same highly integrated QCA4002 (DNSA-141) and QCA4004 (DNSA-144) Wi-Fi components (image 1) by Qualcomm. The SPI interface allows for a quick and easy connection to an MCU-based system environment. For this purpose, the corresponding open source API drivers, available as C-code on the said support website, will have to be ported to the host MCU.

In both cases, users benefit from the fact that the entire TCP/IP protocol stack and higher protocols such as HTTP, DHCP, and DNS and encryptions are already integrated in the QCA4002/4 modules. As a result, no in-depth Wi-Fi skills are required for development, and users can instead focus their attention on the core applications on their host MCU. The QCA4002/4 thus operates as a "black box" which, although it can be controlled from the outside, executes all network processes using its internal CPU.

Image 2 shows the software architecture of the QCA4002/4 modules. All protocols/functions below the red line are covered by the integrated network processor and the hardware (MAC and PHY), while the API (application programming interface) and applications run on the host MCU. As the arrows indicate, the API allows direct access to each individual protocol layer, allowing users themselves to manage the distribution of the protocol function between the host MCU and QCA4002/4. So it is possible, for instance, to circumvent the entire TCP/IP stack and address MAC and PHY directly from the host MCU if, e.g. users want to use their own stack in the operating system.

Despite the fact that the QCA4002/4 parts already integrate several RF components, many customers shy away from the efforts of an own RF design and the subsequent calibration and certification procedures. To relieve them from this last burden, the two module solutions offer a quick, simple, and cost-optimized system integration. Measuring only 20x25mm (DNSA-141, image 3 and 4) and 20x42mm (DNSA-144, image 5 and 6) the modules can be addressed via SPI with the exact same API as QCA4002/4. Of course, the modules also support the low power features integrated in the QCA4002/4, such as, for instance, Low-Power-Listen, Green-Tx-Power-Saving, or IEEE-Sleep-Mode (sleep: 130µA / 2 ms wake up, suspend: 10 µA/ 35 ms wake up). Instead of the dual-band functionality, the second antenna connection of DNS-144 can be used for reception diversity, allowing for a more stable wireless connection and thus a higher range. Support for Rx/Tx diversity, however, is only available at 2.4GHz.